A rotary cutting tool which comprises a plurality of cutting inserts and which cuts a workpiece through rotation has become common. The cutting inserts are arranged so as to be spaced from one another, and each of the cutting inserts is mounted on a body of the rotary cutting tool with a cutting edge of the cutting insert facing outward. The respective cutting edges of the cutting inserts are arranged such that at least parts of rotation trajectories of the cutting edges overlap with one another.
Further, a cutting insert (see Patent Document 1) is known in which cutting edges thereof are each divided into portions by grooves referred to as nicks, and a cutting insert is also known in which cutting edges thereof are each provided with irregularities. These cutting inserts can each reduce cutting resistances by separating chips generated during cutting into small pieces; however, portions which remain uncut are produced in a machined surface of a workpiece. Therefore, when using either of the above cutting inserts by being mounted on the above rotary cutting tool, the arrangement of each cutting edge needs to be adjusted such that portions which remain uncut by a cutting edge are cut by another following cutting edge.
Patent Document 2 discloses a rotary cutting tool in which the arrangement of each cutting edge can be adjusted. In such rotary cutting tool, each cutting insert is mounted on a body via a cartridge. A screw is arranged between a wall surface of the body and an outer side surface of the cartridge, and the body is provided with a threaded hole into which the screw is screwed. A distance between the wall surface of the body and the outer side surface of the cartridge is varied by adjusting the screwing of the screw, whereby the arrangement of each cutting edge can be adjusted.
With the configuration of mounting a cutting insert on a body via a cartridge, as in the rotary cutting tool disclosed in Patent Document 2, when, for example, an excessive force works on the cutting insert, the cartridge will fracture ahead of the body. This prevents fracturing of the body, which is expensive, and allows the rotary cutting tool to restart cutting by way of the replacement of the cartridge alone.